1. Field of the Invention
The present disclosure relates to a method of extracting the height of an object and a footprint surface position of the object from a single satellite image or aerial photographs devoid of meta information.
2. Description of the Related Art
Recently, ordinary people also have a chance to approach a high-resolution image map or 3-dimensional building model via the internet. As a representative image map of furnishing such information, Google Earth or the like exist.
When using software called “Sketchup” unfolded by Google, a general person may easily make a 3-dimension building model and put it up on an image map of Google Earth.
Like this, a high-resolution image map and 3-dimension building map generation become of interest to non-experts as well, researches related to 3-dimension building model generation has been conducted from the past. (Jae-Hong Oh et al. 2007; Kwang-Jae Wee et al. 2007; Sung-Hyuk Jung and Jae-Ki Lee, 2008: Bohn, 2004; Frueh et al., 2004; Fruh and Zakhor, 2003; Lafarge et al., 2008; Zhang et al., 2003). Many of the researches focused on a precise building model generation employing various data and a city model generation using this (Kwang-Jae Wee et al, 2007; Sung-Hyuk Jung and Jae-Ki Lee, 2008; Fruh and Zakhor, 2003; Lafarge et al., 2008; Zhang et al., 2003), or performed an experiment put emphasis on a finite building texture generation or an automatic building texture generation (Jae-Hong Oh et al, 2007; Bohn, 2004; Frueh et al., 2004).
On the one hand, representative conventional technology for extracting 3-dimension information of an object may be categorized by these approaches: stereoscopic, multi-sensory and monoscopic.
In general, many applications for extracting three-dimensional information of an object from images may use an approach based on a stereo camera modeling using a stereo image or more images.
Since such a method needs to perform a camera modeling for each image, there is a problem of necessarily obtaining a ground control points for each image, and since there needs to use more than two images, there may be disadvantages such as a comparatively complicated process and high-cost.
Many methods using a single image have used an approach of estimating a height using a length of a vertical line between a roof corner of the object and a footprint corner of the objet or an approach by measuring the length of a shadow.
Herein, a previous method, that is, a method using the length of the vertical line or a method using the length of the shadow, requires meta information and all of the methods require visible footprint of the object. However in complex urban area, some objects have non-visible footprint and the shadow length of some objects that can't be measured in the image.
Connected with this, in ‘METHOD FOR EXTRACTION OF 3D BUILDING INFORMATION USING SHADOW ANALYSIS’ (Registration Patent 10-0647807, 2006.11.13) overcame the above-described in some part by a method of simulating a vertical line and a shadow of an object and projecting it onto an image by an azimuth and an elevation angle of a light source and a camera.
However, even in this method, there is a problem that meta information such as azimuth and elevation angles of a light source and a camera in those times of photographing the image is necessary.
On the one hand, methods using elevation data such as ‘LiDAR’ can extract accurate a height of objects, but there are disadvantages such as complex data processing and high-cost.
In short, the above-described prior arts need to use material of high-cost such as LIDAR, two or more images, or, even in a case of using a single image, meta information.